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Old 07-13-2011, 02:48 PM   #1
benav
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Distribution: Slackware 14.0
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Three disk partitioning questions (fdisk)


I'm using fdisk and cfdisk that come with the Slackware 13.37 installation DVD (64 bit), to partition a new 640GB hard drive. The hard drive is in a laptop which had Win7 on it but never booted or set up that OS. This is my first time using fdisk/cfdisk to partition a drive.

I used cfdisk, which created my partitions. When I then run "fdisk -l" to double-check, this is what I get:

Code:
Disk /dev/sda: 640.1 GB, 640135028736 bytes
255 heads, 63 sectors/track, 77825 cylinders, total 1250263728 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 4096 byes
I/O size (minimum/optimal): 4096 bytes / 4096 bytes
Disk identifier: 0xd8d86525

   Device Boot      Start         End      Blocks   Id  System
/dev/sda1   *          63       96389       48163+  83  Linux
Partition 1 does not start on physical sector boundary.
/dev/sda2           96390      594404      249007+  82  Linux Swap
Partition 2 does not start on physical sector boundary.
/dev/sda3          594405    40596254    20000925   83  Linux
Partition 3 does not start on physical sector boundary.
/dev/sda4        40596255  1250263727   604833736+  83  Linux
Partition 4 does not start on physical sector boundary.
So question 1 is: Is this "not starting on physical sector boundary" stuff a problem, and if so, how do I fix it?

Question 2 is: Every tutorial I've seen for fdisk has /dev/sda1 starting at sector 1. Is starting at 63 OK? (Though my desktop has /dev/sda1 at 63 and it works fine.)

(Question 2b is: When I tried to use fdisk to create the partitions, it wouldn't create /dev/sda1 any lower than 2048. Why would that be?)

When I run "fdisk /dev/sda", I get:
Code:
The device presents a logical sector size that is smaller than the physical sector size. Aligning to a physical sector (or optimal I/O) size boundary is recommended, or performance may be impacted.
Question 3 is: How do I do this recommended alignment?

Thanks!
 
Old 07-13-2011, 03:03 PM   #2
markush
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Hello benav,

don't panic. The message that a partition doesn't start on the physical sector boundary doesn't matter.

To your 2. question, this is ok, take the default-value which is suggested by fdisk.

Another point: if you don't want to install Windows, create one extended partition on the whole disk and then create logical partitions within the extended one. This helps you to get rid of the 4-partition boundary. It is great nonsense to create only 4 partitions on a 640GB-drive.

If you ever want to install (for example) one of the BSDs, create 3 primary partitions. But as well create an extended partition on the (bigger) rest of the disk. This is much more flexible. Here the output of fdisk -l on my laptop (320GB)
Code:
samsung:~# fdisk -l

Disk /dev/sda: 320.1 GB, 320072933376 bytes
255 heads, 63 sectors/track, 38913 cylinders, total 625142448 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x096716b2

   Device Boot      Start         End      Blocks   Id  System
/dev/sda1            2048    31459327    15728640   27  Hidden NTFS WinRE
/dev/sda2   *    31459328    31664127      102400    7  HPFS/NTFS/exFAT
/dev/sda3        31664128   138487807    53411840    7  HPFS/NTFS/exFAT
/dev/sda4       138487808   625137344   243324768+   5  Extended
/dev/sda5       138487871   211897349    36704739+  83  Linux
/dev/sda6       498241958   625137344    63447693+  83  Linux
/dev/sda7       211899398   222139397     5120000   82  Linux swap
/dev/sda8       222141446   253598725    15728640   83  Linux
/dev/sda9       253600774   358458373    52428800   83  Linux
/dev/sda10      358460422   498239909    69889744   83  Linux

Partition table entries are not in disk order
I hope you understand what I mean

Markus
 
Old 07-14-2011, 12:51 PM   #3
benav
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Hi Markus

Thanks for your response.

I created 4 primary partitions because that's the recommendation in the Slackware How-to, intending to mount them as /boot, swap, / and /home. You're saying that if I started instead with one extended partition over the whole disk, I can create more than 4 primary partitions?
 
Old 07-14-2011, 12:58 PM   #4
markush
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Not primary, the partitions inside an extended partition are "logical" partitions. On modern Linux-systems (like Slackware) you will have no disadvantages with logical partitions.

Note that the Slackbook is relatively old. Primary partitions are only useful if you want to run Windows or one of the BSDs beside your Linux (dualboot). But if you once decide to dualboot several Linux-distributions you are much more flexible with a big extended partition where you can create lots of logical partitions.

Markus
 
Old 07-14-2011, 05:22 PM   #5
Robert.Thompson
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http://computer-forensics.sans.org/b...t-drives-e512/
 
  


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